1. Field of the Invention
The present invention relates to an ophthalmic laser surgical apparatus for ablating eye tissue by a laser beam.
2. Description of Related Art
As an ophthalmic laser surgical apparatus for ablating eye tissue by a laser beam, there is known an apparatus constructed to ablate a cornea by an excimer laser beam, thereby correcting a refractive error of an eye.
And now, the excimer laser beam has the property of being absorbed into water and therefore an ablation rate at which the cornea is irradiated and ablated by the excimer laser beam depends on a quantity of water (a water content) on the cornea. As the cornea becomes dry and the water quantity thereof decreases, the ablation rate increases. As the water quantity increases, on the contrary, the ablation rate decreases. This difference in water quantity and others are factors leading to an error of an ablation amount, that is, an error in refractive correction. To avoid such disadvantages, a sequence of a surgical operation and a time needed therefor have been standardized to maintain a constant degree of dryness (a water quantity) of a cornea. However, this depends on individual experiences of operators largely.